14 April 2005
Eccentric behaviour
The planets of our Solar System are all in nearly circular orbits, as expected of the products of coagulation and accretion in a protostellar disk. Yet most of the 150-plus extrasolar planets so far detected around nearby stars are in eccentric orbits. Observations of the three giant planets around upsilon Andromedae — the 'Rosetta stone' of planetary dynamics — suggest that these orbital eccentricities can be explained if the planets start life in nearly circular orbits and are later perturbed by interaction with another planet now lost from the system. The study of orbital eccentricity is relevant to models of planet formation, and to astronomers interested in the extent of the so-called habitable zones of terrestrial planets.
Planet-planet scattering in the upsilon Andromedae system
ERIC B. FORD, VERENE LYSTAD & FREDERIC A. RASIO
Nature 434, 873–876 (2005); doi:10.1038/nature03427
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